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1500 questions
10
votes
4 answers
Operating proceedures: testing an HT against a repeater?
Assuming proper licensing for the frequency, what is the proper operating procedure to test whether an HT works and is within range of a (documented as open, 2M or 440) club repeater?
Should one wait till someone comes on the repeater, and ask them…
hotpaw2
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10
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1 answer
Why do SDR control apps have two frequency settings?
Why do many SDR control apps have two frequency settings, even when the app is designed or set up only for listening to or decoding one signal? Should the two SDR frequency controls be set differently or the same? If different, how much for which…
hotpaw2
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10
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1 answer
How does a switching mixer multiply the two signals?
I understand what a mixer does, and when I see it in a block diagram it's obvious what purpose it serves and how it fits in the overall design of the radio.
However, when I look at the schematics and see how it's created, I don't understand how it…
Adam Davis
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10
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4 answers
Real world performance of magnetic loop antennas?
I was investigating about magnetic loop antennas. In a paper about them I found some bold claims:
and
This almost sounds too good to be true, considering a lot of us hams are surronded by city noise and this paper claims the noise would be much…
hjf
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10
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1 answer
How do I design a round or square coaxial transmission line to have a specific impedance?
Certain Hex Beam antennas use a coaxial center support post to send the RF to each antenna section, which is superior, in terms of maintenance, to a post with screw terminals connected by short lengths of coax used in previous designs.
I'd like to…
Adam Davis
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10
votes
1 answer
CW on phone band
In the U.S., regulations permit CW operations throughout the amateur bands. That makes the phone section of a band look tempting when the CW/digital part of the band is busy with a contest. I wonder if my friends and I can reasonably have our…
Wayne Conrad KF7QGA
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10
votes
4 answers
Better explanation for beyond-line-of-sight VHF signal reach than "lower curvature to radio waves"
I am currently studying for the Technician Exam and have come across an answer to a question I think is ridiculous. The question is:
Why do VHF/UHF signals usually travel somewhat farther than visual line-of-sight distance between two…
Dave G
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10
votes
3 answers
What is the record for the highest non-automated over-the-air CW WPM speed?
Related to this question, but using humans, and in an actual QSO, not lab conditions:
Is there a record for QSO QRQ speed? And, if so, what is the record for the highest non-automated over-the-air CW/Morse Code WPM rate?
And, if so, are there…
hotpaw2
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10
votes
3 answers
Local phonetic alphabets
In Russia hams use two phonetic alphabets - the regular one (Alpha, Beta, Charlie, ...) and a localized one (Анна, Борис, Цапля, ...). When a ham calls CQ in Russian (which by the way is pronounced not "CQ" but "Всем-всем") she uses Russian phonetic…
Aleksander Alekseev - R2AUK
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10
votes
2 answers
If two antennas of 50 Ω and 377 Ω have VSWR=1:1, then which one is more efficient?
If there are two antennas of 50 Ω and 377 Ω (same as the intrinsic impedance of air) impedance with 0 $\Omega$ ohmic resistance, and they are exactly matched with their transmission line, then which antenna is more effective in terms of radiating…
kaka
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10
votes
2 answers
If someone transmits on 151.88 MHz and I listen on 151.18 MHz, how likely would I hear their transmission?
I have a cheap baofeng uv-5r, and I sometimes hear an intermittent transmission which pulses past the squelch threshold with periods of dead space between, roughly 0.75 seconds or less.
My job uses a repeater and radioreference.com lists the used…
Wolfgang Steele
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10
votes
3 answers
Why does ARRL license examination procedure preclude students from discovering what questions they got wrong on licensing tests
I got my Amateur Extra ticket some time ago. I was able to discover what my score was (the number of questions I got wrong). However, my examiner was not able to tell me specifically which questions I had answered incorrectly, and to this day it…
LCS
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10
votes
5 answers
Audio frequency used for Morse code in licensing exams?
Back when Morse code proficiency was required for certain radio licenses, what audio frequency was used by the exam tapes, equipment or examiner that generated the Morse code audio? Was there a legal or recommended testing standard for this audio…
hotpaw2
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10
votes
4 answers
Understanding power supply requirements
I have a basic question about power supply requirements for typical transceivers. I'm looking at the specs for a Kenwood TM-V71A, which is a 50W mobile transceiver.
I figured that a 50W transceiver running on a 12V(-ish) power supply would pull…
larsks
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10
votes
5 answers
Are there formulae to calculate capacitance and inductance of an antenna?
How to calculate internal impedance of a dipole antenna? Its resistance has two components ie wire resistance and radiation resistance, both these can be calculated using formula. Are there formula to calculate capacitance and inductance of an…
tgnhbv
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